pre-equilibrium in the formation of iminodiazonium (ID) ion and that the N2 liberation from the ID ion is rate-determining. Under high azide concentration conditions, where the effective reactant is the ID ion, the reaction gave a linear Hammett plot with a ρ value of −0.50. The observed substituent effects on the rate and the product selectivity imply that path bifurcation on the way from the rate-determining
Transition metal-free asymmetric and diastereoselective allylic alkylation using Grignard reagents: construction of vicinal stereogenic centers via kinetic resolution
作者:David Grassi、Alexandre Alexakis
DOI:10.1039/c4sc01003e
日期:——
The first transition metal-free diastereoselective and enantioselective asymmetricallylicalkylation (AAA) has been disclosed leading to the construction of vicinal tertiary/quaternary centers via a kinetic resolution protocol starting from readily available starting materials. This procedure is chemically appealing since no consecutive AAA or stereoselective metal-catalyzed/chiral ligand AAAs are
Baeyer–Villiger monooxygenase-catalyzed kinetic resolution of racemic α-alkyl benzyl ketones: enzymatic synthesis of α-alkyl benzylketones and α-alkyl benzylesters
作者:Cristina Rodríguez、Gonzalo de Gonzalo、Daniel E. Torres Pazmiño、Marco W. Fraaije、Vicente Gotor
DOI:10.1016/j.tetasy.2009.03.018
日期:2009.6
The application of three BVMOs for the enantioselective oxidation of 3-phenylbutan-2-ones with different substituents in the aromatic moiety is described. By choosing the appropriate biocatalyst and substrate combination, chiral ketones and esters can be obtained with excellent enantiopurities. This methodology could also be applied to the resolution of racemic alpha-alkyl benzylketones with longer alkyl chains as well as with two substituted alpha-substituted benzylacetones. A kinetic analysis revealed that the BVMOs studied effectively convert all tested compounds showing that the enzymes are tolerant towards the substrate structure while being highly enantioselective. These properties render BVMOs as valuable biocatalysts for the preparation of compounds with high interest in organic synthesis. (C) 2009 Elsevier Ltd. All rights reserved.
Vinyl cations. 12. Mechanism of reaction of cis- and trans-3-phenyl-2-buten-2-yl triflates. Evidence for vinylidene phenonium ions